Apparatus and method for measuring the time evolution of carriers propogating within submicron and micron electronic devices

Abstract

An apparatus for determining and displaying the time evolution profile of electron carriers present within a submicron or micron device comprises a laser for generating a beam of ultrafast pulses of ultraviolet light. A first beam splitter splits each pulse into a transmitted beam and a reflected beam. The transmitted beam travels through a time delay circuit, and is then converted into a train of ultrafast electrical pulses which are transmitted to the device. The reflected beam is focused on the device. An electron detector, also focused on the device, collects the ejected electrons resulting from the interaction of the light pulse and electrical pulse to produce an electrical signal. The signal is then magnified in intensity by an amplifier and directed at a cathode ray tube to cause an image to appear thereon. A SIT vidicon camera converts the image into an electrical signal and transmits the signal to a computer. The computer generates a time evolution profile from the signal received which is sent to a monitor for display.

What is claimed is: 
     
       1. Apparatus for measuring the time evolution profile of electron carriers present within an electronic device, the electronic device having a front surface and a rear surface and a size of about a micron or less, the apparatus comprising: a) means for generating a beam of pulses of light, said pulses of light being in the order of picoseconds or less;   b) means for splitting said beam into first and second beams;   c) means for focusing said second beam onto the entire front surface of the device;   d) means for receiving said first beam and outputting a train of electrical pulses said electrical pulses being on the order of about a picosecond;   e) means for transmitting said electrical pulses to the device;   f) impedence matching circuitry attached to said device;   g) time delay means interposed along the path of said first beam for selectively changing the path length traveled by said first beam so that the light pulses and electrical pulses can be made to intersect at different locations on the electronic device; and   h) electron microscope means focused on the front surface of the device for creating images representing the number and origin of electrons ejected by the device.   
     
     
       2. The apparatus of claim 1 and furthe including means focused on the imaging means for converting the images into electrical signals. 
     
     
       3. The apparatus of claim 2 and further including means for processing said electrical signals to generate a time evolution profile of the carriers within the device. 
     
     
       4. The apparatus of claim 3 and further including means for displaying the time evolution profile produced by said processing means. 
     
     
       5. The apparatus as recited in claim 1 wherein said electron microscope means focused on the device for creating images representing the number and origin of electrons ejected by the device comprises an electron detector for collecting the ejected electrons to produce an electrical signal, an amplifier connected to said electron detector for magnifying the intensity of the electrical signal, and a cathode ray tube for displaying a light image proportional in intensity to the intensity of the electrical signal. 
     
     
       6. The apparatus as recited in claim 5 wherein said means for producing a train of electrical pulses comprises a PIN photodiode. 
     
     
       7. The apparatus as recited in claim 5 wherein said means for producing an electrical signal comprises a photoconductive switch. 
     
     
       8. Apparatus for determining and displaying a time evolution profile of electron carriers present within a device that is micron sized or less, the device having a front surface and a back surface, the apparatus comprising: a) a streak camera tube having a front and a back, an opening in the front and having disposed therein spatial filtering means, an accelerating mesh, a pair of sweeping electrodes, a microchannel plate, a phosphor screen, and bias voltage means;   b) means for removably mounting the device in the opening at the front of the streak camera tube with the front surface of the device facing into said streak camera tube;   c) means electrically connected to the device for producing an electrical pulse which is transmitted through the device, said pulse being on the order of about a picosecond;   d) means for irradiating the entire front surface of the device with a pulse of light, said pulse of light being on the order of picoseconds or less;   e) whereby, electrons are ejected from the front surface of the device into the streak camera tube in the direction of said phosphor screen when the light pulse and the electrical pulse overlap spatially and temporally on the device;   f) means for synchronizing the activation of said sweep electrodes with the arrival of the ejected electrons thereat;   g) whereby the ejected electrons, before impinging on said phosphor screen, are angularly deflected by the sweeping electrodes as a function of time so as to create a streak image on the phosphor screen;   h) means focused on the phosphor screen for converting the streak image into an electrical signal;   i) means electrically coupled to said converting means for processing said electrical signal to generate a time evolution profile of the electron carriers within the device; and   j) means for displaying said time evolution profile.   
     
     
       9. Apparatus as recited in claim 8 wherein said means for removably mounting said device in front of the streak camera tube comprises a pair of brackets and wherein said apparatus further includes first and second microwave launchers, each microwave launcher being mounted on one of the brackets. 
     
     
       10. Apparatus as recited in claim 9 wherein said means for irradiating the inner surface of said device comprises a continuous wave ultraviolet laser. 
     
     
       11. A method for measuring the time evolution profile of electron carriers present within a submicron or micron electronic device, the method comprising: a) generating a beam of pulses of light;   b) splitting said beam into first and second beams;   c) focusing said second beam onto the device;   d) receiving said first beam and outputting a train of electrical pulses;   e) transmitting said electrical pulses through the device;   f) selectively changing the path length traveled by said first beam so that the light pulses and electrical pulses intersect at different locations on the electronic device, and   g) creating images representing the number and origin of electrons ejected by the device on overlapping of said light pulses and said electrical pulses.   
     
     
       12. A method of measuring the time evolution of carriers within an electronic device, the electronic device having a front surface and a rear surface, the method comprising: a. illuminating the entire front surface of the electronic device with a beam of light,   b. simultaneously therewith propagating an electrical pulse through the electronic device,   c. forming a streak image of electrons emitted from the front surface of the device as the electrical pulse propogates through the device, and then   d. processing the streak image.   
     
     
       13. The apparatus as recited in claim 5 wherein said means for producing an electrical signal comprises a microchannel plate photodetector. 
     
     
       14. Apparatus for measuring the time evolution of carriers propogating within an electrical device, the electrical device having a front surface, a back surface and a pair of ends, the apparatus comprising: a. means for producing a beam of pulses of light;   b. means for splitting the beam of pulses of light into two beam parts;   c. means for illuminating the entire front surface with one of said beam parts;   d. means for converting the other beam part into a train of electrical pulses;   e. means for transmitting said train of electrical pulses through the electrical device from one end to the other;   f. electron microscrope means for producing images representing the number and origin of electrons ejected by the device on overlapping of said light pulses and electrical pulses;   g. means for converting the images into electrical signals,   h. computer means for processing said electrical signals; and   i. display means for displaying the processed electrical signals.   
     
     
       15. Apparatus for producing a time evolution profile of electron carriers present within an electrical device, the electrical device having a front surface and a back surface, the apparatus comprising: a. means for generating a beam of light pulses;   b. means for splitting the beam of light pulses into first and second beam parts;   c. means for converting said second beam part into a train of electrical pulses;   d. a streak camera tube having therein an accellerating mesh, sweeping electrodes and a phosphor screen;   e. means for mounting said electrical device in the front of said streak camera tube with said front surface facing inward;   f. means for transmitting said electrial pulses to said electrical device;   g. means for irradiating the entire front surface of said electrical device with said first beam part;   h. whereby electrons emitted therefrom an overlapping of said light and electrical pulses will travel down said streak tube be amplified, deflected and strike said phosphor screen, forming therein a streak image;   i. means for recording said streak image; and   j. means for processing and displaying said recorded streak image.